A circuit assembly in which a circuit board and a heat dissipation plate that dissipates the heat generated in the circuit board to the outside overlap each other is known.
In such a circuit assembly, if a metal bus bar is disposed on the back side of the circuit board (the surface on which the heat dissipation plate is placed), the heat generated from the electronic components mounted on the circuit board is relatively efficiently transferred to the heat dissipation plate via the bus bar, which has high heat conductivity, and is dissipated to the outside. However, if no bus bar is disposed, the heat generated from the electronic components is difficult to be transferred to the heat dissipation plate, and thus the temperature of the circuit assembly and the inside of the apparatus accommodating the circuit assembly may become high.
Also, like the conventional coil described in JP H7-94342A, if a base made of synthetic resin is provided between a circuit board and a core, heat conductivity to a heat dissipation plate may further decrease, the temperature inside the case of the apparatus may become high, and the performance of electronic components may deteriorate.
The technique disclosed in the present specification has been completed based on the above-mentioned circumstances, and an object is to provide a circuit assembly having excellent heat dissipation.